This invention relates to a unit for containing a solution to be optically analyzed.
It has already been suggested that a number of small containers or receptacles be placed on a rotor and a solution in each receptacle be analyzed photometrically by means of a light beam which intersects the path described by the receptacles and by measuring the intensity of the light beam issuing from each receptacle.
A known analyser employing this suggestion comprises a rotor which is formed with a number of radial recesses each communicating with an analysis receptacle disposed at the outside end of the recess. Each such recess is divided into at least two compartments adapted to receive a product for analysis and at least one reagent, respectively. The centrifugal force arising from rotation of the rotor has the effect of displacing the liquid from the inner compartment towards the outer compartment and then of transferring the resulting mixture to the analysis receptacle.
The main disadvantage of such rotorsis that they need cleaning after each analysis before being reused, so that the time wasted is considerable in respect of both cleaning and loading the apparatus with the reagents and samples.
In endeavours to obviate this disadvantage a rotor based on the same underlying idea but which is discarded after use and which is mounted releasably on a rotating support was studied. Such rotors are relatively costly, and so it is a costly business to use a new rotor for each new series of analyses.
Yet another disadvantage is the design of the analysis receptacle. The light beam passes through only some of the solution to be analyzed in all the receptacles, and so the number of molecules which are to be detected and which the light beam encounters depends upon the concentration of the mixture and upon the thickness of the layer of liquid through which the light beam passes. Consequently, the quantity of the sample, the quantity of the or each reagent and vessel dimensions are further factors affecting measurement accuracy.